The wireless local access network (WLAN) is a point-to-multipoint communications system, that is, one access point (AP) communicates with multiple terminal stations (STA). In WLAN communications, mainly a channel contention mechanism is used. The STA listens on a channel before sending data, and sends the data or a request message to the WLAN network once finding that the channel is not occupied by others. It is likely that multiple STAs and multiple APs simultaneously listen on a channel and simultaneously send data or a request message to the WLAN network, and therefore, a sending conflict is caused. In this case, the WLAN decentralizes contention by using a backoff window mechanism, to reduce a conflict probability. However, as a quantity of users that access the WLAN network increases, the contention conflict probability dramatically rises; and an increasing quantity of users sends uplink data and receives downlink data via the WLAN network, resulting in reduction of data transmission efficiency in the WLAN network.